2.83: assign same materials for objects created by array modifier
If your house base model is a continuous mesh (no loose parts), once the modifier is applied, go into edit mode, select everything and press P &gt; By Loose Parts.
Go back into object mode with TAB.
With everything still selected, Right click &gt; Set Origin &gt; To geometry.
Press CTRL+ L &gt; Object Data. Now when you modify one object's materials, they will all update.
In the end, while everything is still selected, go to Object &gt; Relations &gt; Make Single User &gt; Object &amp; Data and then you will be able to tweak each individual house separately.
Obviously it is better to do it before applying the modifier to avoid any of this.
PS, next time please take more time to write your question so there is less back and forth in the comments :)